1. Field of the Invention
The present invention relates to air assist fuel injectors, and, more particularly, to an assembly of air assist fuel injectors and a method of assembling air assist fuel injectors.
2. Description of the Related Art
Conventional fuel injectors are configured to deliver a quantity of fuel to a combustion cylinder of an engine. To increase combustion efficiency and decrease pollutants, it is desirable to atomize the delivered fuel. Generally speaking, atomization of fuel can be achieved by supplying high pressure fuel to conventional fuel injectors, or atomizing low pressure fuel with pressurized gas, i.e., xe2x80x9cair assist fuel injection.xe2x80x9d
FIG. 1 illustrates a conventional air assist fuel injector 20 mounted to an air/fuel rail 30. The rail 30 houses a conventional fuel injector 40 and also defines a mount for the air assist fuel injector 20. The conventional fuel injector 40 and the fuel rail 30 are configured such that a metered quantity of fuel is delivered from the fuel injector to the air assist fuel injector 20. Additionally, the rail 30 includes a number of passageways 42 that deliver pressurized air to the air assist fuel injector 20. The air assist fuel injector 20 atomizes the low pressure fuel with the pressurized air and conveys the air and fuel mixture to the combustion chamber of an engine (not illustrated).
As illustrated in FIG. 1, the pressurized air from the air/fuel rail 30 and the metered quantity of fuel from the conventional fuel injector 40 enter the air assist fuel injector 20 through an inlet in the center of an armature 26. Thereafter, the fuel and air travel through the interior of a poppet 24, and exit the poppet through small slots near the end or head of the poppet. The poppet 24 is attached to the armature 26, which is actuated by energizing a solenoid 22. When the solenoid 22 is energized, the armature 26 will overcome the force of a spring 28 and move toward a leg 30. Because the poppet 24 is attached to the armature, the head of the poppet will lift off a seat 32 so that a metered quantity of atomized fuel is delivered to the combustion chamber of an engine.
The configuration of two and four stroke engines dictate the external dimensions of the air assist fuel injector 20. Conventionally, separate air assist fuel injectors are manufactured for two and four stroke engine applications to satisfy the different dimensional requirements of the two applications. For example, two stroke engines often require a shorter air assist fuel injector than that required for four stroke engine applications because of strict space constraints directly over the head of the two stroke engine. In contrast, four stroke engine applications often require a narrower air assist fuel injector than that required for two stroke engine applications because of strict space constraints in and around the head of the four stroke engine. Additionally, four stroke engine applications often require a longer air assist fuel injector than that required for two stroke engine applications because the air assist fuel injector must extend into the cam valley, but avoid the valve components and any water passageways. Hence, two stroke engine applications have very tight height restrictions, requiring short air assist fuel injectors, while four stroke engine applications have very tight diameter restrictions, requiring long and very small diameter air assist fuel injectors.
Because of these different dimensional requirements, a single, one-size, air assist fuel injector unfortunately cannot satisfy both two stroke and four stoke commercial applications. Hence, conventional air assist fuel injectors for two stroke engine applications and four stoke engine applications are independently manufactured and thus do not share common parts, especially solenoids. For more than a decade, this constraint has proven to be particularly problematic in attempts to economically manufacture air assist fuel injectors for both two and four stroke applications.
In light of the previously described problems associated with manufacturing conventional air assist fuel injectors, one object of the many embodiments of the present invention is to provide air assist fuel injectors for both two and four stroke engines that have one or more common parts but also satisfy the dimensional and functional requirements of these applications.
In furtherance of this object, an additional aim of the many embodiments of the present invention is to provide methods of assembling air assist fuel injectors with one or more common parts for both two and four stroke engine applications.
Other objects, advantages and features associated with the embodiments of the present invention will become more readily apparent to those skilled in the art from the following detailed description. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modification in various obvious aspects, all without departing from the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not limitative.